[all-commits] [llvm/llvm-project] c99908: [GlobalISel] Port some basic shufflevector undef c...

[Jessica Paquette via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: c999084619a61daffac39f0ec9ea3c801e5a8823
      https://github.com/llvm/llvm-project/commit/c999084619a61daffac39f0ec9ea3c801e5a8823
  Author: Jessica Paquette <jpaquette at apple.com>
  Date:   2020-03-19 (Thu, 19 Mar 2020)

  Changed paths:
    M llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h
    M llvm/include/llvm/Target/GlobalISel/Combine.td
    M llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
    M llvm/test/CodeGen/AArch64/GlobalISel/prelegalizercombiner-undef.mir

  Log Message:
  -----------
  [GlobalISel] Port some basic shufflevector undef combines from the DAGCombiner

Port over the following:

- shuffle undef, undef, any_mask -> undef
- shuffle anything, anything, undef_mask -> undef

This sort of thing shows up a lot when you try to bugpoint code containing
shufflevector.

Differential Revision: https://reviews.llvm.org/D76382